These studies are designed to futher explore the long-term effects of open and closed experimental trauma on rabbit knees. Articular tissues will be studied biochemically and morphologically. Biochemical studies involve lysosomal enzyme and synthetic enzyme measurements in the affected synovium, and histochemical staining of synovium and cartilage. Morphologic studies involve gross, microsopic and ultrastructural (transmission and scanning electron microscope) studies of synovium and cartilage. Previous studies have shown that some forms of open trauma in the rabbit knee are completely reversible at 20 weeks. This study continues these previous experiments over 100 weeks, and adds studies of closed intra-articular trauma (ligament disruption, and patellar contusion). In addition, further development of an artifical joint system using labelled articular chondrocytes grown in monolayer culture, incubated with the experimental synovium, will be carried out. The development of this system will add an in vitro parameter to the study of cartilage degradation by synovium.